Hitherto, many reports have been made on transition metal complexes utilizable in organic synthesis reactions, for example, transition metal complex catalysts for use in asymmetric synthesis reactions such as asymmetric hydrogenation reaction, asymmetric isomerization reaction, and asymmetric silylation reaction. Among such transition metal complexes, most of the complexes in which optically active tertiary phosphine compounds are coordinated to transition metals such as ruthenium, rhodium, and palladium show excellent efficiency when used as catalysts in asymmetric synthesis reactions. For the purpose of further enhancing the efficiency of this kind of catalysts, a large number of phosphine compounds having special structures have been developed so far [see Kagaku Sosetsu (The Elements of Chemistry) 32, "Chemistry of Organometallic Complexes" pp. 237-238 (1982), edited by The Chemical Society of Japan]. 2,2'-Bis(diphenylphosphino)-1,1,-binaphthyl (hereinafter referred to as "BINAP") is one of the especially useful phosphine compounds, and a rhodium complex and a ruthenium complex each containing BINAP as a ligand have been reported in JP-A-55-61937 and JP-A-61-63690, respectively. (The term "JP-A" as used herein means an "unexamined published Japanese patent application".) It has also been reported that a rhodium complex (JP-A-60-199898) and a ruthenium complex (JP-A-61-63690) each containing 2,2'-bis[di-(p-tolyl) phosphino]-1,1'-binaphthyl (hereinafter referred to as "p-T-BINAP") as a ligand give good results when used in asymmetric hydrogenation reaction and asymmetric isomerization reaction.
However, there have been cases where according to the kind of the reaction to be conducted or to the reaction substrate therefor, sufficient selectivity, conversion, and durability cannot be obtained even when the above phosphine complexes are used.
In order to overcome the above-described problem, the present inventors have conducted intensive studies on many kinds of phosphine compounds. As a result, it has now been found that a BINAP derivative in which lower alkyl groups are introduced at the 3-position and 5-position in the phenyl groups thereof is far more effective in improving selectivity and conversion in asymmetric synthesis than BINAP and p-T-BINAP. The present invention has been completed based on this finding.